A new study finds that men with prostate cancer that has spread to nearby lymph nodes, who have a significant risk of dying from the disease, can benefit from the addition of radiation therapy to treatments that block the effects of testosterone.

The findings imply that the almost half of patients with node-positive disease nationwide who had not received combination therapy were not receiving the treatment that could best control their tumor and possibly save their lives. The report from investigators at the Massachusetts General Hospital (MGH) Cancer Center in Boston and the American Cancer Society was published in the Journal of the National Cancer Institute (2015; doi:10.1093/jnci/djv119).

"Our analysis of a large national database revealed that adding radiation therapy to androgen-deprivation therapy decreased the risk of death in these patients by 50% over 5 years," said senior author Jason Efstathiou, MD, DPhil, of the MGH Cancer Center and Department of Radiation Oncology.

"It appears that more aggressive local management of prostate cancer confined to the pelvis can offer more durable disease control, prevent the disease from spreading further, and, for some patients, even provide a potential cure."

Whether prostate cancer has spread from the prostate gland to nearby lymph nodes can be determined either by biopsy or imaging, and current tumor-staging practices put patients with node-positive disease in the same category as those whose tumor has metastasized to other parts of the body, such as bone or lung.

Common thinking has been that tumors not confined to the prostate gland cannot be cured but can sometimes be controlled and patients' survival extended by androgen-deprivation therapy (ADT) radiation therapy, or other treatments. ADT blocks testosterone's stimulation of tumor growth. Efstathiou noted that the findings of this study potentially have important implications for staging systems.

Current practice guidelines from the National Comprehensive Cancer Network support treating node-positive cancer with either ADT alone or with ADT plus radiation. While some evidence has suggested that adding radiation therapy improves outcomes for node-positive disease, limited data to support that possibility have been reported.

The current study analyzed information from the National Cancer Data Base to examine treatment practice across the country and compare patient outcomes.

In a population of more than 3,500 hundred men diagnosed with node-positive prostate cancer from 2004 to 2011, the research team found that, while almost 52% had received ADT plus radiation, 32% received ADT alone, 6% received only radiation, and 10% received neither.

Focusing on a statistically matched group of 636 patients, which included 318 who were treated with ADT alone and 318 who received ADT plus radiation therapy, revealed that the death rate among those receiving combination therapy was around 50% lower than it was in patients receiving ADT alone over the 5 years after diagnosis.

"Optimal management of prostate cancer that has spread to regional lymph nodes remains largely undefined, and our finding that nearly half of such patients may be undertreated despite being at a high risk for cancer death suggests that reevaluation of current practice guidelines may be warranted," said Efstathiou.